Alfalfa Mosaic Virus 
Yellow mottling or mosaic patterns on leaves. Leaf distortion, stunting or puckering in severe cases.  Impacts many types of plants but in alfalfa, young leaves may appear yellow and twisted. Key characteristics: Yellow, irregular mosaic leaf damage.
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Bleeding Canker Disease 
A canker disease showing bleeding and oozing black sap, symptomatically similar to sudden oak death. In Nevada, first noticed on a mature silver maple tree in Reno. Key characteristics: Dark brown bleeding sap on mature trees.
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Boxwood Blight
Symptoms begin with leaf spots and progress to die back with characteristic sporodochia appearing on the stems. The roots are not affected. Key characteristics: Rapid plant death, white spots.
Learn more about the Boxwood Blight

Citrus Greening Disease or Huanglongbing
Once infected with the disease, citrus trees usually decline within 5 to 12 years. Citrus greening is spread primarily by gnat-sized insects called Asian citrus psyllids. Key characteristics: Burned shoot tips and twisted leaves on new growth, poor fruit.
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Fire Blight 
Apple or pear branch tips look scorched, with brown or black leaves hanging on them. Sometimes a whitish to light tan fluid seeps out of the fruit. Key characteristics:  Limbs are infected first, shepherd’s-crook shaped.
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Fusariam Wilt 
Palm disease often transmitted to healthy palms via pruning saws that are not disinfected after being used on diseased palms. Diseased trees often appear generally distressed and can be hard to spot. Key characteristics: Palm fronds show an external brown strip, browning and wilt.
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Gladiolus Rust 
Outbreaks have occurred in California. Gardeners growing gladiolus should be vigilant, especially on nursery plants; this disease has been intercepted on cut gladiolus flowers in both commercial shipments and passenger baggage. Key characteristics: Yellow to red blister spots on the leaves of the plant. Can occur on live plants or cut flowers.
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Pine Needle Blight 
In northern Nevada, cases of pine needle blight appear to be increasing on some species of pine. Can have a variety of causes. Key characteristics: “Needle blight” is a general term; the dieback usually starts at the tip of the needle and may be brown, red or gray.
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Phytophthora (many types)
Phytophthora species have been associated with widespread plant decline and mortality in California wildlands and Nevada foothills. Key characteristics: Some species have been associated with sudden oak death and bleeding cankers. Some species impact the western United States, while some have, so far, been limited to Europe.
Learn More About Phytophthora: USDA LEARN ABOUT PHYTOPHTHORA KERNOVIAE: NV AG

Plum Pox
Plum pox, also called sharka, is considered one of the most devastating viral diseases worldwide of stone fruit, including peaches, apricots, plums, nectarines, almonds, and sweet and tart cherries.  Key characteristics: Distorted and discolored fruit, reduced yield and shortened tree life.
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Potato Cyst Nematodes 
Potato Cyst Nematodes are soil-borne organisms that do not infest potato tubers. The pests infest feeder roots and have been found in Idaho and other U.S. states. Key characteristics: Visable root damage, poor root development and early plant death.
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Potato Wart Disease
 This is caused by the soil-borne fungus Synchytrium endobioticum. It affects cultivated potato and a number of wild species. It is mostly well controlled in the U.S. Key characteristics: Warty, cauliflower-like swellings on underground eyes. 
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Powdery Mildew
Powdery Mildew is a fungus that produces spores that are spread by the wind. This fungal disease has a wide host range. Key characteristics:  Mildew-covered the leaves, stems and buds, as though sprinkled with dusting powder.
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Ralstonia Solanacerum
Ralstonia solanacerum is a bacterial pathogen that causes several diseases on a wide range of plants. It infects certain vegetables and ornamental crops, especially in the Nightshade family. Key characteristics: Wilting, leaf curling and damage. 
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Root-Knot Nematode
Root-knot nematode (Meloidogyne spp.) is a parasite on and in plant roots. Infected roots have galls, causing them to look as if they have been knotted. This pest can attack tomatoes, peppers, carrots, onions, cactuses, roses, fruit trees and many ornamentals. Key characteristics: Stunting, leaf drop and mid-day wilting.
Learn more about the Root-Knot Nematode

Sclerotinia Sclerotiorum 
White mold disease is caused by the fungus Sclerotinia sclerotiorum. It affects more than 400 plant species. Commonly known as stem rot, cottony rot, watery soft rot, drop, crown rot and blossom blight. This has been a problem for Nevada commercial growers. Key characteristics: White mold disease of many types of vegetables.
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Soybean Rust
Two fungal species, Phakopsora pachyrhizi and P. meibomiae, cause soybean rust and are spread primarily by windborne spores. P. pachyrhizi, the more aggressive type, has been found in the U.S., including in California. Key characteristics: Tan lesions and rust-colored pustules on soybean.
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Sudden Oak Death
The water mold Phytophthora ramorum is the causal agent of several plant diseases. Has been found to be a cause of sudden oak death in Oregon and California. Key characteristics: Cankers, leaf lesions and sudden tree death. 
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Thousand Cankers Disease
Thousand cankers disease has been found in many western states. Dieback and mortality of eastern black walnut (Juglans nigra) has increased over the last decade due to this disease. Key characteristics: Branch mortality, numerous small cankers and evidence of tiny bark beetles.
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